1. Field of the Invention
The present invention relates to organic materials for EL (electroluminescent) devices and to EL devices, and more particularly it relates to organic materials for EL devices which exhibit electroluminescence upon the application of a voltage, and to EL devices which employ the above-mentioned organic materials.
2. Description of the Related Art
EL devices employing luminescent materials which exhibit electroluminescence upon the application of a voltage are conventionally used in backlights for displays of OA machines such as word processors and for automobile meters and the like.
Although inorganic compounds have conventionally been used as the luminescent materials for such EL devices, high driving voltages have been required when inorganic compounds for EL devices are caused to emit high-intensity light.
Recently, therefore, research has been conducted in regard to organic compounds for EL devices, which allow lower driving voltages (see, for example, C. W. Tang and S. A. VanSlyke: Appl. Phys. Lett. 51. 913 (1987)).
Thin-film EL devices employing such organic compounds are able to have lower driving voltages in comparison with the conventional inorganic compounds for EL devices.
However, the light emitted by organic compounds for EL devices capable of emitting light at sufficient intensity is usually in the green band (492-577 nm).
Consequently, EL devices employing organic luminescent materials have had an inappropriate color for use in backlights of OA machine displays, etc.
On the other hand, EL devices require multiple colors for their use in displays and the like.